From 6b148934c4cc1992dda774bff87acc28c9961aa1 Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@airbus.com>
Date: Mon, 1 Jul 2019 17:40:36 +0200
Subject: Factorisation de code dans l'implémentation à seuil
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Plus facile à  lire, je trouve (pas besoin de  se demander "c'est quoi
cette division ?" à chaque fois).
---
 src/add_threshold/tweakey.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/add_threshold/tweakey.c b/src/add_threshold/tweakey.c
index 888e893..8f531d9 100644
--- a/src/add_threshold/tweakey.c
+++ b/src/add_threshold/tweakey.c
@@ -29,7 +29,9 @@ tweakey schedule, where the tweak and the key are split into two shares.
 #include "tweakey.h"
 
 
-#define LANES_NB   (TWEAKEY_BYTES/LANE_BYTES)
+#define LANES_NB       (TWEAKEY_BYTES/LANE_BYTES)
+#define TWEAK_LANES_NB (TWEAK_BYTES/LANE_BYTES)
+#define KEY_LANES_NB   (KEY_BYTES/LANE_BYTES)
 
 
 void tweakey_state_init(
@@ -72,8 +74,7 @@ void tweakey_state_extract(
         }
     }
 
-
-    for (size_t j=0; j<(KEY_BYTES / LANE_BYTES); j++)
+    for (size_t j=0; j<KEY_LANES_NB; j++)
     {
         const uint8_t *TKj_Y = TK_Y + j*LANE_BYTES;
 
@@ -103,7 +104,7 @@ void tweakey_state_update(uint8_t TK_X[TWEAKEY_BYTES], uint8_t TK_Y[KEY_BYTES])
 {
     /* Skip lane 0, as it is multiplied by the identity matrix. */
 
-    for (size_t j=1; j<(TWEAK_BYTES/LANE_BYTES); j++)
+    for (size_t j=1; j<TWEAK_LANES_NB; j++)
     {
         uint8_t *TKj_X = TK_X + j*LANE_BYTES;
 
@@ -113,9 +114,9 @@ void tweakey_state_update(uint8_t TK_X[TWEAKEY_BYTES], uint8_t TK_Y[KEY_BYTES])
         ALPHAS[j-1](TKj_old_X, TKj_X);
     }
 
-    for (size_t j=0; j<(KEY_BYTES/LANE_BYTES); j++)
+    for (size_t j=0; j<KEY_LANES_NB; j++)
     {
-        uint8_t *TKj_X = TK_X + (j + (TWEAK_BYTES/LANE_BYTES))*LANE_BYTES;
+        uint8_t *TKj_X = TK_X + (j + TWEAK_LANES_NB)*LANE_BYTES;
         uint8_t *TKj_Y = TK_Y + j*LANE_BYTES;
 
         uint8_t TKj_X_old[LANE_BYTES];
@@ -123,7 +124,7 @@ void tweakey_state_update(uint8_t TK_X[TWEAKEY_BYTES], uint8_t TK_Y[KEY_BYTES])
         memcpy(TKj_X_old, TKj_X, LANE_BYTES);
         memcpy(TKj_Y_old, TKj_Y, LANE_BYTES);
 
-        ALPHAS[j-1 + (TWEAK_BYTES/LANE_BYTES)](TKj_X_old, TKj_X);
-        ALPHAS[j-1 + (TWEAK_BYTES/LANE_BYTES)](TKj_Y_old, TKj_Y);
+        ALPHAS[j-1 + TWEAK_LANES_NB](TKj_X_old, TKj_X);
+        ALPHAS[j-1 + TWEAK_LANES_NB](TKj_Y_old, TKj_Y);
     }
 }
-- 
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